Generic byte streams

Generic byte-streams. More...

Typedefs
typedef struct svn_stream_t	svn_stream_t
	An abstract stream of bytes--either incoming or outgoing or both.
typedef svn_error_t *(*	svn_read_fn_t )(void *baton, char *buffer, apr_size_t *len)
	Read handler function for a generic stream.
typedef svn_error_t *(*	svn_write_fn_t )(void *baton, const char *data, apr_size_t *len)
	Write handler function for a generic stream.
typedef svn_error_t *(*	svn_close_fn_t )(void *baton)
	Close handler function for a generic stream.
Functions
svn_stream_t *	svn_stream_create (void *baton, apr_pool_t *pool)
	Create a generic stream.
void	svn_stream_set_baton (svn_stream_t *stream, void *baton)
	Set stream's baton to baton.
void	svn_stream_set_read (svn_stream_t *stream, svn_read_fn_t read_fn)
	Set stream's read function to read_fn.
void	svn_stream_set_write (svn_stream_t *stream, svn_write_fn_t write_fn)
	Set stream's write function to write_fn.
void	svn_stream_set_close (svn_stream_t *stream, svn_close_fn_t close_fn)
	Set stream's close function to close_fn.
svn_stream_t *	svn_stream_empty (apr_pool_t *pool)
	Create a stream that is empty for reading and infinite for writing.
svn_stream_t *	svn_stream_disown (svn_stream_t *stream, apr_pool_t *pool)
	Return a stream allocated in pool which forwards all requests to stream.
svn_error_t *	svn_stream_open_readonly (svn_stream_t **stream, const char *path, apr_pool_t *result_pool, apr_pool_t *scratch_pool)
	Create a stream to read the file at path.
svn_error_t *	svn_stream_open_writable (svn_stream_t **stream, const char *path, apr_pool_t *result_pool, apr_pool_t *scratch_pool)
	Create a stream to write a file at path.
svn_error_t *	svn_stream_open_unique (svn_stream_t **stream, const char **temp_path, const char *dirpath, svn_io_file_del_t delete_when, apr_pool_t *result_pool, apr_pool_t *scratch_pool)
	Create a writable stream to a file in the directory dirpath.
svn_stream_t *	svn_stream_from_aprfile2 (apr_file_t *file, svn_boolean_t disown, apr_pool_t *pool)
	Create a stream from an APR file.
svn_stream_t *	svn_stream_from_aprfile (apr_file_t *file, apr_pool_t *pool)
	Similar to svn_stream_from_aprfile2(), except that the file will always be disowned.
svn_error_t *	svn_stream_for_stdout (svn_stream_t **out, apr_pool_t *pool)
	Set *out to a generic stream connected to stdout, allocated in pool.
svn_stream_t *	svn_stream_from_stringbuf (svn_stringbuf_t *str, apr_pool_t *pool)
	Return a generic stream connected to stringbuf str.
svn_stream_t *	svn_stream_from_string (const svn_string_t *str, apr_pool_t *pool)
	Return a generic read-only stream connected to string str.
svn_stream_t *	svn_stream_compressed (svn_stream_t *stream, apr_pool_t *pool)
	Return a stream that decompresses all data read and compresses all data written.
svn_stream_t *	svn_stream_checksummed2 (svn_stream_t *stream, svn_checksum_t **read_checksum, svn_checksum_t **write_checksum, svn_checksum_kind_t checksum_kind, svn_boolean_t read_all, apr_pool_t *pool)
	Return a stream that calculates checksums for all data read and written.
svn_stream_t *	svn_stream_checksummed (svn_stream_t *stream, const unsigned char **read_digest, const unsigned char **write_digest, svn_boolean_t read_all, apr_pool_t *pool)
	Similar to svn_stream_checksummed2(), but always returning the MD5 checksum in read_digest and write_digest.
svn_error_t *	svn_stream_read (svn_stream_t *stream, char *buffer, apr_size_t *len)
	Read from a generic stream.
svn_error_t *	svn_stream_write (svn_stream_t *stream, const char *data, apr_size_t *len)
	Write to a generic stream.
svn_error_t *	svn_stream_close (svn_stream_t *stream)
	Close a generic stream.
svn_error_t *	svn_stream_printf (svn_stream_t *stream, apr_pool_t *pool, const char *fmt,...)
	Write to stream using a printf-style fmt specifier, passed through apr_psprintf() using memory from pool.
svn_error_t *	svn_stream_printf_from_utf8 (svn_stream_t *stream, const char *encoding, apr_pool_t *pool, const char *fmt,...)
	Write to stream using a printf-style fmt specifier, passed through apr_psprintf() using memory from pool.
svn_error_t *	svn_stream_readline (svn_stream_t *stream, svn_stringbuf_t **stringbuf, const char *eol, svn_boolean_t *eof, apr_pool_t *pool)
	Allocate *stringbuf in pool, and read into it one line (terminated by eol) from stream.
svn_error_t *	svn_stream_copy3 (svn_stream_t *from, svn_stream_t *to, svn_cancel_func_t cancel_func, void *cancel_baton, apr_pool_t *pool)
	Read the contents of the readable stream from and write them to the writable stream to calling cancel_func before copying each chunk.
svn_error_t *	svn_stream_copy2 (svn_stream_t *from, svn_stream_t *to, svn_cancel_func_t cancel_func, void *cancel_baton, apr_pool_t *pool)
	Same as svn_stream_copy3() but the streams are not closed.
svn_error_t *	svn_stream_copy (svn_stream_t *from, svn_stream_t *to, apr_pool_t *pool)
	Same as svn_stream_copy3(), but without the cancellation function or stream closing.
svn_error_t *	svn_stream_contents_same (svn_boolean_t *same, svn_stream_t *stream1, svn_stream_t *stream2, apr_pool_t *pool)
	Set *same to TRUE if stream1 and stream2 have the same contents, else set it to FALSE.
svn_error_t *	svn_string_from_stream (svn_string_t **result, svn_stream_t *stream, apr_pool_t *result_pool, apr_pool_t *scratch_pool)
	Read the contents of stream into memory, returning the data in result.

---

Detailed Description

Generic byte-streams.

---

Typedef Documentation

typedef svn_error_t*(* svn_close_fn_t)(void *baton)

Close handler function for a generic stream.

See also:

svn_stream_t.

Definition at line 684 of file svn_io.h.

typedef svn_error_t*(* svn_read_fn_t)(void *baton, char *buffer, apr_size_t *len)

Read handler function for a generic stream.

See also:

svn_stream_t.

Definition at line 674 of file svn_io.h.

typedef struct svn_stream_t svn_stream_t

An abstract stream of bytes--either incoming or outgoing or both.

The creator of a stream sets functions to handle read and write. Both of these handlers accept a baton whose value is determined at stream creation time; this baton can point to a structure containing data associated with the stream. If a caller attempts to invoke a handler which has not been set, it will generate a runtime assertion failure. The creator can also set a handler for close requests so that it can flush buffered data or whatever; if a close handler is not specified, a close request on the stream will simply be ignored. Note that svn_stream_close() does not deallocate the memory used to allocate the stream structure; free the pool you created the stream in to free that memory.

The read and write handlers accept length arguments via pointer. On entry to the handler, the pointed-to value should be the amount of data which can be read or the amount of data to write. When the handler returns, the value is reset to the amount of data actually read or written. Handlers are obliged to complete a read or write to the maximum extent possible; thus, a short read with no associated error implies the end of the input stream, and a short write should never occur without an associated error.

Definition at line 669 of file svn_io.h.

typedef svn_error_t*(* svn_write_fn_t)(void *baton, const char *data, apr_size_t *len)

Write handler function for a generic stream.

See also:

svn_stream_t.

Definition at line 679 of file svn_io.h.

---

Function Documentation

svn_stream_t* svn_stream_checksummed	(	svn_stream_t *	stream,
		const unsigned char **	read_digest,
		const unsigned char **	write_digest,
		svn_boolean_t	read_all,
		apr_pool_t *	pool
	)

Similar to svn_stream_checksummed2(), but always returning the MD5 checksum in read_digest and write_digest.

Since:

New in 1.4.

Deprecated:

Provided for backward compatibility with the 1.5 API.

svn_stream_t* svn_stream_checksummed2	(	svn_stream_t *	stream,
		svn_checksum_t **	read_checksum,
		svn_checksum_t **	write_checksum,
		svn_checksum_kind_t	checksum_kind,
		svn_boolean_t	read_all,
		apr_pool_t *	pool
	)

Return a stream that calculates checksums for all data read and written.

The stream stream is used to read and write all data. The stream and the resulting digests are allocated in pool.

When the stream is closed, *read_checksum and *write_checksum are set to point to the resulting checksums, of type read_checksum_kind and write_checksum_kind, respectively.

Both read_checksum and write_checksum can be NULL, in which case the respective checksum isn't calculated.

If read_all is TRUE, make sure that all data available on stream is read (and checksummed) when the stream is closed.

Read and write operations can be mixed without interfering.

The stream passed into this function is closed when the created stream is closed.

Since:

New in 1.6.

svn_error_t* svn_stream_close

(

svn_stream_t *

stream

)

Close a generic stream.

See also:

svn_stream_t.

svn_stream_t* svn_stream_compressed	(	svn_stream_t *	stream,
		apr_pool_t *	pool
	)

Return a stream that decompresses all data read and compresses all data written.

The stream stream is used to read and write all compressed data. All compression data structures are allocated on pool. If compression support is not compiled in then svn_stream_compressed() returns stream unmodified. Make sure you call svn_stream_close() on the stream returned by this function, so that all data are flushed and cleaned up.

Note:

From 1.4, compression support is always compiled in.

svn_error_t* svn_stream_contents_same	(	svn_boolean_t *	same,
		svn_stream_t *	stream1,
		svn_stream_t *	stream2,
		apr_pool_t *	pool
	)

Set *same to TRUE if stream1 and stream2 have the same contents, else set it to FALSE.

Use pool for temporary allocations.

Since:

New in 1.4.

svn_error_t* svn_stream_copy	(	svn_stream_t *	from,
		svn_stream_t *	to,
		apr_pool_t *	pool
	)

Same as svn_stream_copy3(), but without the cancellation function or stream closing.

Since:

New in 1.1.

Deprecated:

Provided for backward compatibility with the 1.4 API.

svn_error_t* svn_stream_copy2	(	svn_stream_t *	from,
		svn_stream_t *	to,
		svn_cancel_func_t	cancel_func,
		void *	cancel_baton,
		apr_pool_t *	pool
	)

Same as svn_stream_copy3() but the streams are not closed.

Since:

New in 1.5.

Deprecated:

Provided for backward compatibility with the 1.5 API.

svn_error_t* svn_stream_copy3	(	svn_stream_t *	from,
		svn_stream_t *	to,
		svn_cancel_func_t	cancel_func,
		void *	cancel_baton,
		apr_pool_t *	pool
	)

Read the contents of the readable stream from and write them to the writable stream to calling cancel_func before copying each chunk.

cancel_func may be NULL.

Note:

both from and to will be closed upon successful completion of the copy (but an error may still be returned, based on trying to close the two streams). If the closure is not desired, then you can use svn_stream_disown() to protect either or both of the streams from being closed. ### TODO: should close the streams ALWAYS, even on error exit

Since:

New in 1.6.

svn_stream_t* svn_stream_create	(	void *	baton,
		apr_pool_t *	pool
	)

Create a generic stream.

See also:

svn_stream_t.

svn_stream_t* svn_stream_disown	(	svn_stream_t *	stream,
		apr_pool_t *	pool
	)

Return a stream allocated in pool which forwards all requests to stream.

Destruction is explicitly excluded from forwarding.

See also:

notes/destruction-of-stacked-resources

Since:

New in 1.4.

svn_stream_t* svn_stream_empty

(

apr_pool_t *

pool

)

Create a stream that is empty for reading and infinite for writing.

svn_error_t* svn_stream_for_stdout	(	svn_stream_t **	out,
		apr_pool_t *	pool
	)

Set *out to a generic stream connected to stdout, allocated in pool.

The stream and its underlying APR handle will be closed when pool is cleared or destroyed.

svn_stream_t* svn_stream_from_aprfile	(	apr_file_t *	file,
		apr_pool_t *	pool
	)

Similar to svn_stream_from_aprfile2(), except that the file will always be disowned.

Note:

The stream returned is not considered to "own" the underlying file, meaning that svn_stream_close() on the stream will not close the file.

Deprecated:

Provided for backward compatibility with the 1.3 API.

svn_stream_t* svn_stream_from_aprfile2	(	apr_file_t *	file,
		svn_boolean_t	disown,
		apr_pool_t *	pool
	)

Create a stream from an APR file.

For convenience, if file is NULL, an empty stream created by svn_stream_empty() is returned.

This function should normally be called with disown set to FALSE, in which case closing the stream will also close the underlying file.

If disown is TRUE, the stream will disown the underlying file, meaning that svn_stream_close() will not close the file.

Since:

New in 1.4.

svn_stream_t* svn_stream_from_string	(	const svn_string_t *	str,
		apr_pool_t *	pool
	)

Return a generic read-only stream connected to string str.

Allocate the stream in pool.

svn_stream_t* svn_stream_from_stringbuf	(	svn_stringbuf_t *	str,
		apr_pool_t *	pool
	)

Return a generic stream connected to stringbuf str.

Allocate the stream in pool.

svn_error_t* svn_stream_open_readonly	(	svn_stream_t **	stream,
		const char *	path,
		apr_pool_t *	result_pool,
		apr_pool_t *	scratch_pool
	)

Create a stream to read the file at path.

It will be opened using the APR_BUFFERED and APR_BINARY flag, and APR_OS_DEFAULT for the perms. If you'd like to use different values, then open the file yourself, and use the svn_stream_from_aprfile2() interface.

The stream will be returned in stream, and allocated from result_pool. Temporary allocations will be performed in scratch_pool.

Since:

New in 1.6

svn_error_t* svn_stream_open_unique	(	svn_stream_t **	stream,
		const char **	temp_path,
		const char *	dirpath,
		svn_io_file_del_t	delete_when,
		apr_pool_t *	result_pool,
		apr_pool_t *	scratch_pool
	)

Create a writable stream to a file in the directory dirpath.

The file will have an arbitrary and unique name, and the full path will be returned in temp_path. The stream will be returned in stream. Both will be allocated from result_pool.

If dirpath is NULL, use the path returned from svn_io_temp_dir(). (Note that when using the system-provided temp directory, it may not be possibly to atomically rename the resulting file due to cross-device issues.)

The file will be deleted according to delete_when.

Temporary allocations will be performed in scratch_pool.

Since:

New in 1.6

See also:

svn_io_open_unique_file3()

svn_error_t* svn_stream_open_writable	(	svn_stream_t **	stream,
		const char *	path,
		apr_pool_t *	result_pool,
		apr_pool_t *	scratch_pool
	)

Create a stream to write a file at path.

The file will be *created* using the APR_BUFFERED and APR_BINARY flag, and APR_OS_DEFAULT for the perms. The file will be created "exclusively", so if it already exists, then an error will be thrown. If you'd like to use different values, or open an existing file, then open the file yourself, and use the svn_stream_from_aprfile2() interface.

The stream will be returned in stream, and allocated from result_pool. Temporary allocations will be performed in scratch_pool.

Since:

New in 1.6

svn_error_t* svn_stream_printf_from_utf8	(	svn_stream_t *	stream,
		const char *	encoding,
		apr_pool_t *	pool,
		const char *	fmt,
			...
	)

Write to stream using a printf-style fmt specifier, passed through apr_psprintf() using memory from pool.

The resulting string will be translated to encoding before it is sent to stream.

Note:

Use APR_LOCALE_CHARSET to translate to the encoding of the current locale.

Since:

New in 1.3.

svn_error_t* svn_stream_read	(	svn_stream_t *	stream,
		char *	buffer,
		apr_size_t *	len
	)

Read from a generic stream.

See also:

svn_stream_t.

svn_error_t* svn_stream_readline	(	svn_stream_t *	stream,
		svn_stringbuf_t **	stringbuf,
		const char *	eol,
		svn_boolean_t *	eof,
		apr_pool_t *	pool
	)

Allocate *stringbuf in pool, and read into it one line (terminated by eol) from stream.

The line-terminator is read from the stream, but is not added to the end of the stringbuf. Instead, the stringbuf ends with a usual '\0'.

If stream runs out of bytes before encountering a line-terminator, then set *eof to TRUE, otherwise set *eof to FALSE.

svn_error_t* svn_stream_write	(	svn_stream_t *	stream,
		const char *	data,
		apr_size_t *	len
	)

Write to a generic stream.

See also:

svn_stream_t.

svn_error_t* svn_string_from_stream	(	svn_string_t **	result,
		svn_stream_t *	stream,
		apr_pool_t *	result_pool,
		apr_pool_t *	scratch_pool
	)

Read the contents of stream into memory, returning the data in result.

The stream will be closed when it has been successfully and completely read.

The returned memory is allocated in result_pool, and any temporary allocations are performed in scratch_pool.

Note:

due to memory pseudo-reallocation behavior (due to pools), this can be a memory-intensive operation for large files.

Since:

New in 1.6